High-voltage fluidic circuit interrupter

ABSTRACT

A semiconducting fluid stream controls arcing between the contacts of a high-voltage circuit interrupter. The fluid stream initially establishes a low-resistance conducting path between the interrupter contacts as they separate when the interrupter is activated. As the spacing between the contacts increases the resistance of the fluid stream also increases. The increased resistance reduces the load current to a low level at which circuit interruption is accomplished without significant arcing. The semiconducting fluid also extinguishes any arc which forms as the interrupter contacts separate.

United States Patent [72] Inventors Wallace L. Bo1ing,dcceased 2,076,352 4/1937 Saint Germain 200/148 H late of Vancouver, Wash. by Dorothea M. 2,084,885 6/ 1937 Biermanns 200/ 148 H Boling, legal representative; 2,279,040 4/1942 Grosse 200/ 148 A Allen L. Kinyon, Vancouver, Wash. 2,303,730 12/1942 Fernier..... 200/ 148 A [21] Appl. No. 862,999 2,382,274 8/1945 Trencham 200/148 H giled d g m- 2 FOREIGN PATENTS atente ct. [73] Assignee The United States of America as "p'esemed by 59cm 1961782 6/1938 Switzer1arid..::: .1: 200/148 H Primary ExaminerRobert S. Macon 1 HIGH-VOLTAGE FLUIDIC CIRCUIT Attorneys-Ernest S. Cohen and Gersten Sadowsky INTERRUPTER Y 7 Claims, 10 Drawing Figs. [52] US. Cl. "200/144l ABSTRACT; A semiconducting fluid stream controls arcing Z ZOO/148 ZOO/150 R between the contacts of a high-voltage circuit interrupter. The [I'll- ..l-l0lh stream establishes a lowqesistance conducting Field 0 Search A, ath between the interrupter contacts as they separate when 143 144 AP the interrupter is activated. As the spacing between the con- References cued tacts increases the resistance of the fluid stream also increases. Theincreased resistance reduces the load current to a low UNITED STATES PATENTS level at which circuit interruption is accomplished without sigl,861,129 5/1932 Milliken 200/148 nificant arcing. The semiconducting fluid also extinguishes 1,912,042 5/1933 Rump 200/150 any arc which forms as the interrupter contacts separate.

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HIGH-VOLTAGE FLUIDIC CIRCUIT INTERRUPTER BACKGROUND OF THE INVENTION Circuit interrupters are commercially available in which a nonconducting, arc-extinguishing fluid such as inert gas, air or oil is directed into the path of the electric are formed upon opening a circuit to blow out the are as the interrupter contacts separate. Typical examples of prior circuit breakers of this type are found in U.S. Pat. No. 1,861,128, granted to H. Milliken on May 31, I932; U.S. Pat. No. 2,076,357 granted to J. M. Saint Germain on Apr. 6, i937; U.S. Pat. No. 2,303,730, granted to B. M. H. P. Fernier on Dec. 1, 1942; and U.S. Pat. No. 2,382,274, granted to H. Trencham on Aug. 14, 1945. While prior circuit interrupters are suitable for interrupting high-voltage AC circuits they are inadequate for interrupting high-voltage DC circuits for thefollowing reasons: The successful interruption of high-voltage AC circuits by the devices of the prior art depends upon the periodic reversal characteristic of alternating current, which decreases to zero at a rate of 120 times per second. When a high-voltage AC arc is drawn between switch contacts, the arc establishes and quenches completely for each half-cycle of current until the contacts separate a distance sufficient to prevent restrike. This useful feature of AC systems is not available for the interruption of DC systems, which are inherently maintained at constant potential. Consequently, when high-voltage DC circuits are interrupted by the circuit interrupters of the prior art, an arc is drawn to great length and bridges the switch contacts after the interrupter is completely open. With the circuit interrupter of this invention this undesirable result is avoided.

SUMMARY OF THE INVENTION with one another when the interrupter circuit is closed. To interrupt an electrical circuit, the contact assemblies are displaced from physical contact with one another. As the contact assemblies first separate, the high-power system voltage tends to ionize the air in the short space between them. lf this ionization is not controlled, an arc forms between the contact assemblies. A semiconducting fluid is employed in this invention to control this tendency to form an arc.

The semiconducting fluid is stored in tanks under high pressure and released through electrically conducting nozzles during operation of the interrupter. One conducting nozzle is electrically connected to each contact assembly. When released, the semiconducting fluid flows in a continuous stream from electrical contact with one contact assembly, into electrical contact with the other assembly, forming a conductive bridge between them.

The two contact assemblies include pairs of main and auxiliary contacts. The main contacts are used for normal transmission of load current when the interrupter circuit is closed. The auxiliary contacts cooperate with the semiconducting fluid streams to control arcing when the main contacts of the interrupter are opened. In operation, the flow of semiconducting fluid is initiated just prior to separation, or breaking of the main contacts. A fluid stream from one nozzle is directed onto a contact plug which extends within the nozzle from the opposite contact assembly. This fluid stream establishes an auxiliary low-resistance path for current flow between the two contact assemblies. The fluid stream from the other nozzle is initially directed into the space between the main contacts to blow out any are which forms as the main contacts physically separate. As the physical separation between the contact assemblies increases the two fluid streams intersect, increasing the effective conductive length of the electrically conducting fluid path between the contact assemblies. As the effective conductive length of the fluid path increases, its resistance to the flow of electrical current similarly increases, and the load current, therefore, decreases.

When the contacts have separated a distance sufficient to prevent restrike of an arc between them, the intersection point of the semiconducting fluid streams enters a breakup zone in each individual fluid stream. In this zone the fluid streams are discontinuous and exhibit rapidly decreasing conductivity, as their resistance approaches infinity. At this point the fluid circuit becomes nonconductive and flnal interruption of the circuit occurs. Any arcing between the fluid streams is blown out by the turbulence of the streams in the breakup zone.

Alternate forms of the invention employ one or more fluid streams flowing between translatable or rotatable contact assemblies. While two conducting streams one stationary and one movable are used in the preferred embodiment of the invention, even a single variable resistance bridge between the separating contact assemblies adds a significant improvement over prior circuit interrupters. Other circuit interrupters into which the teachings of the invention may be incorporated are well known in the prior art, as indicated in part in the above background of the invention.

Therefore, one object of this invention is an electric circuit interrupter which employs a semiconducting fluid for minimizing arcing when a circuit is interrupted.

Another object of this invention is an electric circuit interrupter in which a semiconducting fluid establishes a relatively low-resistance auxiliary current path when the main contacts of the interrupter separate.

Another object of this invention is an electric circuit interrupter in which a semiconducting fluid blows out the initial are which occurs during the separation of the main interrupter contacts.

Another object of his invention is an electric circuit interrupter in which a semiconducting fluid acts as a continuously variable increasing resistance for decreasing the load current as the interrupter contacts separate. Another object of this invention is an electric circuit interrupter in which a semiconducting fluid blows out the are which is initiated at final interruption of the circuit after the load current has been reduced.

These and other objects of the invention are apparent in this specification and drawing which describe the preferred embodiment of the invention.

DESCRIPTION OF THE DRAWING FIG. 1 is a plan view of a semiconducting, fluid-break circuit interrupter, showing the interrupter contacts in partially opened position.

FIG. 2 is a side view of the circuit interrupter shown in FIG.

FIGS. 3A to 3D show the operating sequence for opening the contacts of the circuit interrupter shown in FIGS. 1 and 2.

FIGS. 4A and 4B show a second embodiment of a semiconducting, fluid-break circuit interrupter in closed and open circuit configuration.

FIGS. 5A and 5B show a third embodiment of a semiconducting, fluid-break circuit interrupter in closed and open circuit configuration.

DESCRIPTION OF THE PREFERRED EMBODIMENT A semiconducting fluid-break circuit interrupter 10 is shown in FIGS. 1 and 2. As best seen in FIG. I, the interrupter 10 includes two electrically isolated contact assemblies 12 and 14 for alternately making and breaking electrical continuity between two sections of a power transmission system, as illustrated by load conductors 16 and 18. The contact assemblies 12 and 14 are supported upon a baseplate 20 by insulating columns 22 and 24 which include ceramic insulators 26 and spacers 28 and 30, as best seen in FIG. 2. One of the contact assemblies 12 is mounted in a fixed position on the baseplate 20. The other contact assembly 14 is mounted for rotation on the baseplate about the vertical axis of the insulating column 24.

Circuit interruption between the power system sections occurs when the movable contact assembly 14 is rotated away from electrical contact with the fixed contact assembly 12. Circuit continuity occurs when a contact blade 32 on the movable contact assembly 14 is rotated into physical and electrical contact with the spaced lips of a side break disconnect contact 34 on the fixed contact assembly 12.

The movable column 24 and contact assembly 14 are rotated by a force applied to a lever arm 36. The force is transmitted to the column 24 through a linkage 38 which includes a pivoted connector 40, an insulated switch pull rod 42, an offset. pivoted connector 44, a pivot lever arm 46, and a pivot table 48. Each end of the pivot table 48 rotates relative to the other end upon a central shaft 50 which extends through the base plate 20, as seen in FIG. 2. The pivot table 48 is attached at one end to the insulating column 24, and at the other end to the base plate 20, and causes relative rotation between the insulating column and baseplate when the pivot arm 46 is rotated.

As the insulating column 24 rotates, it is stabilized by an insulated support 52. The support 52 extends from a foundation structure 56, upon which the interrupter 10 is mounted, to a lead connector 54. A bolt 60 holds the lead connector 54 to the top of the insulating column 24 with a slip fit, permitting the bolt to turn within the connector. The lead connector 54 and the load conductor 18, which is secured to it by a clip 58, remain stationary when the insulating column 24 rotates, pivoting on the shaft 50 and the bolt 60 as the interrupter circuit is opened and closed.

A pair of substantially horizontal arms 62 and 64 extend from the top of the movable insulating column 24 in the general direction of the fixed insulating column 22. The arms 62 and 64 are joined to the opposite ends of a spacing collar 66 and bolted to the upper insulator 26 on the movable insulating column. The bolt 60, which pivots within the lead connector 54, is concentrically secured to the same spacing collar 66.

The ends of the horizontal arms 62 and 64 opposite the insulating column 24 are drawn together and the switch contact blade 32 is sandwiched between them. The triangular framework formed by the arms 62 and 64, and the spacing collar 66, as shown in FIG. 2, maintains the vertical elevation of the contact blade 32 while, at the same time, enabling movement of the blade in a horizontal plane for making and breaking contact with the side break disconnect contact 34 on the fixed contact assembly 12. A flexible woven wire cable 68 forms a conductive bridge between the upper horizontal arm 62' and the lead connector 54 to establish electrical continuity between the contact blade 32 and one load conductor 18. The side break disconnect contact 34 on the top of the fixed insulating column 22 is connected to the other load conductor 16 through a conductive spacing block 70, a contact plate 72 and a connecting clip 58 to complete a continuous conducting path between the load conductors.

On contact assemblies 12 and 14 there are two electrically conductive. nozzles 74 and 76 which are maintained at the electrical potential of the disconnect 34 and the contact blade 32, respectively. One nozzle 74 is secured by a conducting sleeve 78 to the contact plate 72 on the fixed contract assembly 12. The other nozzle 76 is secured by a conducting sleeve 80 to the contact blade 32. The nozzles 74 and 76 are separately connected by hoses 82 and 83 to independent pressurized fluid tanks 84 and 85, respectively. The nozzles 74 and 76 are oriented so that their axes of symmetry, which define .the direction of fluid flow, intersect for the relative positions of the fixed and movable contact assemblies 12 and 14.

On the end of contact blade 32 there is a contact plunger 86 oriented in the direction of rotation of the contact blade and alignedwith the throat 88 of the fixed nozzle 74. When the interrupter circuit is closed, the contact plunger 86 extends into the throat of the nozzle without contacting the nozzle. As the 0 switch blade 32 through the plunger 86, forming a set of aux- III iliary contacts in parallel with the main contacts 32 and 34. The diameter of the throat 88 of the nozzle 74 relative to that of the plunger 86 is sufficient to insure a uniform flow of semiconducting fluid and, therefore, to prevent turbulence which might cause electrical discontinuity between the nozzle and plunger.

In closed position the contact blade 32 and side break disconnect contact 34 are in physical and electrical contact, as shown in FIG. 3A. As the main contacts 32 and 34 separate, a continuous semiconducting fluid stream 94, discharged from the movable nozzle 76, blows out any current arcing between the contacts, as shown in FIG. 3B. The movable stream strikes the sleeve 78 which surrounds the fixed nozzle 74 and establishes electrical continuity between the two nozzles, forming a second set of auxiliary contacts in parallel with the first set of auxiliary contacts. Further rotation of movable contact 32 directs the movable semiconducting fluid stream 94 into the path of the stream 92 from the stationary nozzle 74, as shown in FIG. 3C. At this point the entire load current through the interrupter 10 is carried by the semiconducting fluid stream 92 which flows from the fixed noule 74. A part of this current is carried to the contact blade 32 through the contact plunger 86, and the remainder is carried to the contact blade through the movable fluid stream 94 and movable nozzle 76.

Increased separation of the contact blade 32 and the noule 74, as the interrupter is further opened, increases the effective length of the conductive path through the semiconducting fluid stream. The resistance of the fluid stream is proportional to the length of the stream. Therefore, as the length of the stream between the contact 32 and nozzle 74 increases, the resistance to current flow through the fluid stream also increases. The gradual increase in the resistance of the conductive fluid path as the interrupter is opened causes a gradual reduction of the load current transmitted through the interrupter 10. This reduced current is less susceptible than the full load current to arcing when the circuit is finally broken.

Interruption of the circuit occurs when the semiconducting fluid streams from the nozzles 74 and 76 stop conducting current. This stoppage can occur, in two ways either through the physical separation of the streams by rotation of the movable stream away from the fixed stream, or through rapid reduction of the conductivity of the streams by their physical breakup into droplets at a point removed from the nozzles. Actual separation of the streams requires a high-pressure continuous flow to maintain conductivity over a long distance. As the streams separate, the force of gravity tends to curve them downward so that each stream must be maintained at the same flow rate if the two streams are to intersect. These design requirements make actual separation of the streams less desirable than the alternate interruption through stream breakup.

Stream breakup occurs when, at a point removed from the nozzles 74 and 76, the uniform flow of the semiconducting fluid streams is overcome by frictional and gravitational forces, as shown in FIG. 3D. The point of breakup can be regulated by the size and shape of the nozzles 74 and 76, and by the pressure of the fluid. The point of breakup is chosen to occur at a distance from the nozzles 74 and 76 which is sufficient to reduce the current flowing through the semiconducting fluid stream to a level at which minimum arcing will occur when final interruption takes place. When the two fluid streams 92 and 94 intersect at the point of stream breakup,

minor arcing between the streams occurs as interruption of the load current begins. This minor low-current arcing is blown out by turbulence of the streams at the breakup point. The flow of semiconducting fluid is then stopped. At this time the contact blade 32 and the disconnect 34 are sufficiently spaced to prevent restrike in air when the line voltage recovers to full level immediately after the final interruption.

The semiconducting'fluid used in the interrupter can be salt water or any other fluid having adequate conductivity, in-

cluding most ionic solutions of metallic salts. Dielectric fluids such as oil, which are ordinarily used in blowout-type'circuit breakers, are not sufficiently conductive for use in this fluid break interrupter. The fluid is stored under high pressure in the two tanks 84 and 85 which are electrically isolated from ground by insulated supporting columns 96 and 97. The tanks are charged through valves 99 on their tops. The flow of semiconducting fluid out of the tanks'and into the hoses 82 and 83 is controlled by the pneumatic valves 90 which are connected between the output of each tank and a corresponding hose. The pneumatic valves 90 are simultaneously activated by electrically controlled air valves 101 when operation of the interrupter 10 is initiated. The electrically controlled air valves 101 receive compressed air from a supply tank (not shown) and transfer the air for opening and closing the pneumatic valves. The electric air valves 101 are driven by a battery 98 through a switch 100 which is manually activated at the time the operation of the interrupter 10 is initiated, and deactivated after interruption is completed. The remote electropneumatic control of the semiconducting fluid streams removes the danger of grounding between the load and control circuits and insures safe operation of the interrupter 10.

Alternate forms of the invention are schematically shown in FIGS. 4 and 5. In each figure the operation of the main contacts has been omitted for the sake of clarity. Suitable main contacts, as shown in FIGS. l-3, would be provided for operation of the interrupter under load conditions. In FIGS. 4A and 4B a circuit interrupter 1 10 is shown with two conducting nozzles 112 and 114 which, in closed position are linearly opposed in electrical contact with one another, and in open position are contrarotated away from contact with one another. The nozzles are supported for rotation upon a baseplate 115 by insulating columns 116 and 118, as shown in FIG. 4-A. Each nozzle is offset from the opposite supporting column to prevent fouling of the column by semiconducting fluid when circuit interruption occurs. Semiconducting fluid is supplied to the nozzles through rubber supply hoses 120. For interruption of an electric power circuit a semiconducting fluid 122 is discharged from both nozzles 112 and 114 as the nozzles are contrarotated by a set of gears 124, cooperating with the insulating column 116 and 118. Two intersecting semiconducting fluid streams 126 and 128 establish a path for the flow of current between load conductors 130 and 132 until the conducting nozzles 112 and 114 are sufficiently spaced to prevent restrike, as shown in FIG. 4B.

In FIGS. 5A and 53 a circuit interrupter 150 is shown with two electrically conducting nozzles 152 and 154, which in closed position are in electrical contact with one another, and in open position are spaced from one another. The conducting nozzles are supported on a baseplate 156 by insulating columns 158 and 160. Each nozzle is oriented at an angle with respect to the other to prevent fouling of the insulating column by the semiconducting fluid which is supplied to the nozzles 152 and 154 through rubber supply hoses 162. For interruption of an electric power circuit, semiconducting fluid streams are discharged from the nozzles as the nozzles are physically moved away from one another by driving gears 168, cooperating with racks 170. The two semiconducting fluid streams interrupt the electrical current flowing between conductors 172 and 174 in the manner previously described.

It is therefore apparent that a useful device have been shown and described for the safe and efficient interruption of high-voltage electric current. In adapting the exemplary teachings of this disclosure to a specific power transmission environment, numerous modifications within the scope of the invention will be apparent to those of ordinary skill in the art. For example, while the invention is particularly suited to the difficulties of high-voltage DC circuit interruption, it is equally useful for AC applications. The feature of a continuously variable, increasing resistance, fluid conductor can be adapted to the numerous devices which are currently in use for interrupting both AC and DC high-voltage power circuits.

While one embodiment of the invention has been shown in FIGS. l-3 with a conducting fluid path in parallel with the conducting path through the main contacts, alternate arrangements are possible. For example, the side-break disconnect 34 7 could be replaced by a contact mounted concentrically within the fixed nozzle 74 for conductively contacting the contact plunger 86. The initial transfer of current to the fluid stream as the contacts were opened would then be direct, rather than by a parallel path. The single, solid contact plunger, which is shown in FIGS. 1-3 cooperating with a nozzle to form an auxiliary contact, could be replaced by a plurality of hollow, open-ended, concentric tubes. Such tubes would provide greater fluid contact area than a single plunger. and would increase the electrical continuity between the nozzle and plunger.

These and other modifications of the invention will become apparent to those skilled in the art in the light of the above teaching and within the scope of the appended claims.

What is claimed is:

1. A high-voltage electric circuit interrupter comprising:

first and second relatively movable, electrically conducting contact assemblies,

means for electrically connecting one conductor of a pair of load conductors to the first contact assembly and the other conductor of the pair of load conductors to the second contact assembly,

The first contact assembly including a first metallic electrical contact,

the second contact assembly including a second metallic electrical contact in a position for contacting the first electrical contact when the first and second contact assemblies are moved into close physical proximity with one another,

means to relatively move the contact assemblies for making and breaking electrical continuity between the first and second electrical contacts,

means for directing semiconductive fluid streams to establish a variable resistance conductive fluid path between the first and second contact assemblies in parallel with the first and second metallic contacts as continuity between the first and second contacts is broken, the variable resistance increasing as the contact assemblies are moved apart to interrupt an electrical circuit, the means for directing further comprising:

means on the first contact assembly for directing a first independent semiconducting fluid stream into electrical contact with the second contact assembly, and means on the second contact assembly for directing a second independent semiconducting fluid stream into electrical contact with the first contact assembly, the fluid streams from each contact assembly being so oriented for relative movement with the contact assemblies that the streams intersect when the relatively movable first and second contact assemblies are positioned within a segment of the total range of the relative movement of the contact as semblies, and

the means on the first contact assembly for directing a first independent fluid stream into electrical contact with the second contact assembly being so oriented to direct the first independent fluid stream between the first and second contacts as the first and second contact assemblies are initially moved apart in the interruption of an electrical circuit.

2. A high-voltage circuit interrupter as claimed in claim 1 in which the means on the second contact assembly for directing a second independent fluid stream into electrical contact with the first contact assembly includes a nozzle with a hollow throat, and the auxiliary contact includes an elongated plunger positioned on the first contact assembly for extension within the throat of the nozzle when the first and second contacts are closed.

3. A high-voltage electric circuit interrupter as claimed in claim 1 in which:

the means for directing the first and second independent semiconducting fluid streams includes two electrically conducting noules, one of which is mounted in electrical contact with each of the first and second contact assemblies, two pressurized fluid reservoirs, each containing a semiconducting fluid, and two conduits, interconnecting each nozzle with a different one of the two reservoirs for discharging the semiconducting fluid from the contact assembly to which each nozzle is attached onto the other contact assembly. 4. A high-voltage electric circuit interrupter as claimed in claim 1 in which:

the means for establishing a variable resistance conductive path between the first and second contact assemblies includes means for establishing a conductive path for which the resistance gradually increases as the length of the path increases to a selected length, and for which the resistance rapidly reaches infinity when the length of the path between the contact assemblies exceeds the selected length. 5. A high-voltage electric circuit interrupter as claimed in claim 1 in which the means for directing a semiconducting fluid between the first and second contact assemblies includes means for regulating the effective conductive length of the streams, outside of which effective conductive length physical breakup of the streams occurs.

6. A high-voltage electric circuit interrupter as claimed in claim 3 in which the means for directing a semiconducting fluid between the first and second contact assemblies includes means for regulating the eflective conductive lengths of the first and second independent semiconducting fluid streams, outside of which effective conductive length physical breakup of the first and second streams occurs, whereby when the first and second streams intersect at a point outside the effective conductive length of either stream, the resistance of the conductive path between the first and second contact assemblies rapidly reaches infinity.

7. A high-voltage electric circuit interrupter as claimed in claim 1 in which the means for directing a semiconducting fluid between the first and second contact assemblies includes means for regulating the effective conductive lengths of the first and second independent semiconducting fluid streams, outside of which effective conductive length physical breakup of the first and second streams occurs, whereby when the first and second streams intersect at a point outside the effective conductive length of either stream, the resistance of the conductive path between the first and second contact assemblies rapidly reaches infinity. 

1. A high-voltage electric circuit interrupter comprising: first and second relatively movable, electrically conducting contact assemblies, means for electrically connecting one conductor of a pair of load conductors to the first contact assembly and the other conductor of the pair of load conductors to the second contact assembly, The first contact assembly including a first metallic electrical contact, the second contact assembly including a second metallic electrical contact in a position for contacting the first electrical contact when the first and second contact assemblies are moved into close physical proximity with one another, means to relatively move the contact assemblies for making and breaking electrical continuity between the first and second electrical contacts, means for directing semiconductive fluid streams to establish a variable resistance conductive fluid path between the first and second contact assemblies in parallel with the first and second metallic contacts as continuity between the first and second contacts is broken, the variable resistance increasing as the contact assemblies are moved apart to interrupt an electrical circuit, the means for directing further comprising: means on the first contact assembly for directing a first independent semiconducting fluid stream into electrical contact with the second contact assembly, and means on the second contact assembly for directing a second independent semiconducting fluid stream into electrical contact with the first contact assembly, the fluid streams from each contact assembly being so oriented for relative movement with the contact assemblies that the streams intersect when the relatively movable first and second contact assemblies are positioned within a segment of the total range of the relative movement of the contact assemblies, and the means on the first contact assembly for directing a first independent fluid stream into electrical contact with the second contact assembly being so oriented to direct the first independent fluid stream between the first and second contacts as the first and second contact assemblies are initially moved apart in the interruption of an electrical circuit.
 2. A high-voltage circuit interrupter as claimed in claim 1 in which the means on the second contact assembly for directing a second independent fluid stream into electrical contact with the first contact assembly includes a nozzle with a hollow throat, and the auxiliary contact includes an elongated plunger positioned on the first contact assembly for extension within the throat of the nozzle when the first and second contacts are closed.
 3. A high-voltage electric circuit interrupter as claimed in claim 1 in which: the means for directing the first and second independent semiconducting fluid streams includes two electrically conducting nozzles, one of which is mounted in electrical contact with each of the first and second contact assemblies, two pressurized fluid reservoirs, each containing a semiconducting fluid, and two conduits, interconnecting each nozzle with a different one of the two reservoirs for discharging the semiconducting fluid from the contact assembly to which each nozzle is attached onto the other contact assembly.
 4. A high-voltage electric circuit interrupter as claimed in claim 1 in which: the means for establishing a variable resistance conductive path between the first and second contact assemblies includes means for establishing a conductive path for which the resistance gradually increases as the length of the path increases to a selected length, and for which the resistance rapidly reaches infinity when the length of the path between the contact assemblies exceeds the selected length.
 5. A high-voltage electric circuit interrupter as claimed in claim 1 in which the means for direCting a semiconducting fluid between the first and second contact assemblies includes means for regulating the effective conductive length of the streams, outside of which effective conductive length physical breakup of the streams occurs.
 6. A high-voltage electric circuit interrupter as claimed in claim 3 in which the means for directing a semiconducting fluid between the first and second contact assemblies includes means for regulating the effective conductive lengths of the first and second independent semiconducting fluid streams, outside of which effective conductive length physical breakup of the first and second streams occurs, whereby when the first and second streams intersect at a point outside the effective conductive length of either stream, the resistance of the conductive path between the first and second contact assemblies rapidly reaches infinity.
 7. A high-voltage electric circuit interrupter as claimed in claim 1 in which the means for directing a semiconducting fluid between the first and second contact assemblies includes means for regulating the effective conductive lengths of the first and second independent semiconducting fluid streams, outside of which effective conductive length physical breakup of the first and second streams occurs, whereby when the first and second streams intersect at a point outside the effective conductive length of either stream, the resistance of the conductive path between the first and second contact assemblies rapidly reaches infinity. 